In the clip, Deb (Carpenter) is avoiding her brother -- she hasn't talked to him in weeks and skipped LaGuerta's memorial -- and is shutting everyone out as she claims to be working a case.

"My life is none of your business," she tells him. "Do you want to know why I'm not returning your calls? It's because I don't want to talk to you and I really don't want to f---ing see you. Why? Because you made me compromise everything about myself that I care about. And I hate you for it. I shot the wrong person in that trailer."

News of Dexter's final season comes after CBS Corp. chief Leslie Moonves, who oversees corporate sibling Showtime, told investors in March that Dexter would end its run this year. Showtime executives had been mum on what the future holds for Dexter, declining to comment on the show's future -- until now.

"We are absolutely writing it with an end in sight, but if we get told otherwise somewhere along the way, we'll take it in a different direction. But we are definitely working toward the finale of the series. We are indeed, yes," executive producer Scott Bucktold The Hollywood Reporter in December following the shocking season-seven finale in which Deb kills LaGuerta.

"When it debuted in 2006, Dexter redefined the genre by taking the anti-hero to new heights and pushing the boundaries of the television landscape," Showtime chairman and CEO Matt Blank said Thursday. "Dexter paved the way for the next generation of award-winning hit Showtime series, and its cultural impact will be felt for years to come."

Added Showtime president of entertainment David Nevins: "Dexter is a landmark franchise for our network, and we cannot wait to unveil the conclusion of this series as we know it to the millions of passionate fans who have supported the show season after season. We'd like to thank Michael, Jennifer and Dexter's indomitable cast, executive producers, writers and crew for eight incredible seasons."

Showtime will use Dexter -- which was renewed a year ago for seasons seven and eight -- as a launching pad for Ray Donovan, moving up its premiere from fall to summer for the first time come June. Season eight -- which will include the return of Yvonne Strahovski as Hannah -- will bow June 30 on Showtime.

During its run, Dexter has been nominated for 25 Emmys, including four for outstanding drama series. Hall picked up five nominations for lead actor in a drama five years in a row (from 2008 to 2012) and has picked up 10 Golden Globe noms. It has won four Emmys and two Globes.

Dexter ranks as Showtime's No. 1-rated series (tied with Homeland). Its seventh-season finale drew 6.2 million weekly viewers -- its highest-rated season yet. The news comes a year after Showtime wrapped the Mary-Louise Parker comedy Weeds, which like Dexter was an early awards-season magnet for Showtime as it ramped up its original scripted fare.

Check out the final season trailer, below, which picks up six months after LaGuerta's slaying.